Solving the electronic structure problem for nanoscale systems remains a computationally challenging problem. The numerous degrees of freedom, both electronic and nuclear, make the problem impossible to solve without some effective approximations. Here we illustrate some advances in algorithm developments to solve the Kohn-Sham eigenvalue problem, i.e. we solve the electronic structure problem ...

Time-dependent density functional theory (TDDFT) can be viewed as an exact reformulation of time-dependent quantum mechanics, where the fundamental variable is no longer the many-body wave function but the density. This time-dependent density is determined by solving an auxiliary set of noninteracting Schrodinger equations, the Kohn-Sham equations. The nontrivial part of the many-body interacti...

Interaction energies for a representative sample of 39 intermolecular complexes are calculated using two computational approaches based on the subsystem formulation of density functional theory introduced by Cortona (Phys. Rev. B 44:8454, 1991), adopted for studies of intermolecular complexes (Wesolowski and Weber in Chem. Phys. Lett. 248:71, 1996). The energy components (exchange-correlation a...

We have tested the performance of the Kohn-Sham orbital approach to obtain the electronic coupling and the energetics for hole transfer (HT) in the guanine-indole pair, using a three-state model. The parameters are derived from the simple DFT calculations with 10 different functionals, and compared with benchmark MS-CASPT2 calculations. The guanine-indole pair is a simple model for HT in DNA-pr...

Early work extending the Kohn-Sham theory to excited states was based on replacing the study of the ground-state energy as a functional of the ground-state density by a study of an ensemble average of the Hamiltonian as a functional of the corresponding average density. We suggest and develop an alternative to this description of excited states that utilizes the matrix of the density operator t...

We present and test a new approximation for the exchange-correlation (xc) energy of Kohn-Sham density functional theory. It combines exact exchange with a compatible non-local correlation functional. The functional is by construction free of one-electron self-interaction, respects constraints derived from uniform coordinate scaling, and has the correct asymptotic behavior of the xc energy densi...

We present an atomic orbital based approximate scheme for self-interaction correction (SIC) to the local density approximation of density functional theory. The method, based on the idea of Filippetti and Spaldin [[1] Phys. Rev. B 67, 125109 (2003)], is implemented in a code using localized numerical atomic orbital basis sets and is now suitable for both molecules and extended solids. After der...

PURPOSE Pulmonary emphysema is the pathological prototype of chronic obstructive pulmonary disease and is also associated with other lung diseases. We considered that observation with different approaches may provide new insights for the pathogenesis of emphysema. PATIENTS AND METHODS We reviewed tissue blocks of the lungs of 25 cases with/without emphysema and applied a three-dimensional obs...

In two recent papers [1,2] we have presented significant portions of an effort to provide a comprehensive mathematical basis for Density Functional Theory. The aim is to be both formally sound and to provide a structural framework for the development of improved approximations. The earlier paper addressed the relationship between symmetry breaking in Kohn-Sham solutions and the essential struct...

A novel discrete variable representation (DVR) is introduced for use as the L 2 basis of the Smatrix version of the Kohn variational method [ Zhang, Chu, and Miller, J. Chem. Phys. 88, 6233 ( 1988) ] for quantum reactive scattering. (It can also be readily used for quantum eigenvalue problems.) The primary novel feature is that this DVR gives an extremely simple kinetic energy matrix (the poten...